1. Field of the Invention
The present invention generally relates to a method for equalizing a received burst signal and, more particularly, is directed to an equalizing system suitable for demodulating a transmitted signal.
2. Description of the Prior Art
A TDMA (time division multiple access) system is known as one type of digital cellular communication system in which a base station and a mobile station are connected via radio waves. According to this TDMA system, six receiving slots, for example, are provided for every channel of the 900 MHz band and in each mobile station an incoming signal in one of the six slots is received for a period of 20 milliseconds at intervals of 120 milliseconds. Six transmission slots are similarly provided for every channel, and in each mobile station an outgoing signal in one of the six transmission slots is similarly transmitted. A reference receiving carrier frequency and a reference transmitting carrier frequency in a single mobile station are different from each other.
When a received signal is equalized by an equalizing apparatus in the base station or mobile station, the received signal is a burst signal which is received for a very short period of time (20 milliseconds) so that the tap convergence of the equalizing filter cannot be made sufficient. There is then the risk that the signal portion corresponding to the original signal portion of the received signal will be dropped out.
Furthermore, although it is proposed that the high speed convergence of the tap is effected by utilizing a nonlinear algorithm based on the feedback loop, there is then the disadvantage that the filter becomes unstable.